The invention concerns the field of tyres and in particular the packaging and handling of tyre casings during their storage and transport.
The constant striving for greater productivity, along with a constant desire to improve the working conditions of those engaged in the field, has led various operators in the sector of industry concerned to optimise the logistical chain by acting to improve the conditions of storage in industrial depots, transport, loading and unloading operations, and the production of batches that are easy to identify and move as required by the needs of delivery or storage area optimisation, while preserving the integrity of the tyres.
A widely used system consists in using pallets whose size is specially chosen to be able to receive tyres of various dimensions and diameters. For example, a pallet currently used in storage depots is described in patent application U.S. Pat. No. 5,259,325, in which the tyres are stored in a stack or roll.
Pallets of this type have the advantages of constituting homogeneous batches of tyres, of being able to be arranged on top of one another to a great height, of being able to be manipulated by mechanical means of the fork-lift truck type, and of providing good protection for the tyres against external aggressions. On the other hand they are less suitable for transport, particularly on long journeys, because of the poor compactness of their loads and because of the need to arrange for the return of the empty pallets.
For transport over long distances it is desirable to fit the largest possible number of tyres into a given volume, regardless of whether it is a truck trailer, a marine container or a railway wagon. A system currently used is to arrange the tyres one above the other in a particular arrangement known as “herring-bone” or else “chain” and then put the volume so constituted under compression so as to optimise the load. These methods are described, for example, in the patent U.S. Pat. No. 5,092,106.
Although very effective for optimising the volume to be loaded, this last method nevertheless has the disadvantage of having to be implemented partly by hand, which is a limiting factor in terms of cost, ergonomics, batch integrity, or even storage.
In effect it is commonly found that each of the systems mentioned above represents an optimum solution for a particular field such as storage or transport, but it is rare for one and the same technical solution to be advantageous all along the logistical chain. This makes it necessary to vary the packaging as a function of the various stages of the said chain, and therefore entails particular handling operations which in part cancel the benefits achieved by choosing the system most suitable for a particular point along the logistical chain.
The purpose of the invention is to contribute towards reducing handling and transport costs, while also improving the ergonomics related to the storage and recovery operations.
It is known from the prior art to produce autonomous unitary packs from a given number of tyres arranged in a herring-bone pattern. These autonomous units, also called batches, can comprise several tens or even one or two hundred tyres depending on the tyre size and on the packaging volume chosen.
Thus, patent U.S. Pat. No. 6,527,499 describes a process which enables unitary packs to be made up in which the tyres are arranged in stacks or more commonly in the configuration called “herring-bone” and are then compressed vertically between two rigid plates, around which are arranged containing means that enable the batch of tyres to be kept under tension. Although compact, these unitary packs have the disadvantage of comprising recyclable supports whose management complicates the organisation of the logistical chain.
Another solution is disclosed in the patent FR 2 243 115, in which a process is described for producing a unitary pack formed from a batch of tyres again arranged in herring-bone configuration, compressed vertically and immobilised by containing means such as bands, straps, packaging fabrics or tension-resistant sheets, whose purpose is to keep the stack in shape and oppose elastic expansion. This process makes it possible to obtain autonomous unitary packs which are sufficiently rigid and can be manipulated without the help of special machinery.
However, the need to immobilise the unitary pack in its compacted condition entails a lengthy and relatively costly operation, whose careful implementation is an important factor for the actual volume and stability of the autonomous unit so formed. In effect, the positioning of the containing means while the unitary pack is kept in its compressed condition is a difficult operation. These two disadvantages limit both the size of the unitary packs and the degree of compression that can be obtained, at the risk of seeing the unitary pack disintegrate during a handling operation.
It is for that reason that patent FR 2 243 115 describes a preferred immobilisation process in which the tyres are stacked in a given order between two rigid end-stops, in such manner that once the compression operation has been carried out, the tyres only expand by a negligible amount because of the longitudinal forces exerted against the wall elements forming the end-stops, which block the elastic expansion of the compressed batch. This last arrangement again relies on the use of pallets comprising special uprights.
The purpose of the present invention is to propose a device and process that overcome the disadvantages mentioned above.
It was observed that by arranging strips by wrapping in quite particular directions around the batch of tyres to be packaged, it was possible to make a device that enables the said wrapping to be done while keeping the batch under compression in a relatively easy way.
This device for packaging tyre casings comprises:                a pre-packaging station where a given number of tyres that constitute a single batch L are arranged within a certain overall size in one or more rows orientated longitudinally along an axis XX′ and arranged in horizontal layers,        a compression station that enables the batch L to be compressed in a direction substantially perpendicular to the plane of the layers,        a packing unit consisting of one or more applicator systems that can position straps of a given width under tension around the batch L, by wrapping around a first, horizontal axis YY′ which is substantially perpendicular to the axis XX′, and by helical winding with variable pitch around a second axis essentially parallel to the direction XX′, and two packing conveyors that can keep the batch L of tyres under compression during the positioning of the straps,        a transfer assembly that can hold the batch of tyres during movements from one station to another,        a clearing station.        
By carrying out the helical winding of the strap simultaneously around the batch and the only downstream part of the packing conveyors, the downstream ends of the said packing conveyors can be disengaged from the space between the straps and the batch of tyres, moving the batch longitudinally relative to the downstream ends of the said packing conveyors by actuating the advance of the said conveyors. The dimensions and form of the packing conveyor must be adjusted so as to facilitate as much as possible the longitudinal sliding of the strap relative to the conveyor.
To ensure good cohesion of the packaged batch of tyres it is preferable to stack the tyres in successive horizontal layers in a “herring-bone” configuration:
Besides, by adjusting the degree of compression of the batch of tyres and the tension and pitch of the helical winding, it is possible to obtain a batch of tyres that can be manipulated easily and directly with the help of a conventional fork-lift truck without previously having to put the batch onto a rigid pallet. The packaged batch has sufficient structural rigidity to prevent its deformation when held at the bottom by the two forks of the truck.
As will be seen later in the context of a particular embodiment of the device, the shape of the batch of tyres can be modified in particular ways that facilitate the introduction of the forks under the packaged batch of tyres.